Question

Describe the shapes of a concave lens and a convex lens

Answer 1

A concave lens ‘caves in’. A convex lens goes out like a bubble-shape. I don’t know of this will help, but use it if you can.

Answer 2

The fact that a double convex lens is thicker across its middle is an indicator that it will converge rays of light that travel parallel to its principal axis. A double convex lens is a converging lens. A double concave lens is also symmetrical across both its horizontaland vertical axis.
This is from google btw.